1. Field of the Invention
This invention relates to character recognition apparatus, and in particular, to the portion of such apparatus for converting the two dimensional feature information derived from an unknown character into one dimensional feature information, such as a sequence of code trains, in order to compare the code trains with those of the reference characters.
2. Description of the Prior Art
Many kinds of character recognition apparatus have been proposed, in some of which, an unknown character to be recognized is first transformed to a quantized matrix signal, namely, two dimensional information after certain preliminary processing, such as rejecting noise components and thinning the lines of the character in order to reduce redundancy and constitute a line width of one bit.
Then, the features of the character, such as the terminal points, the branch points and the line directions, are detected from the matrix signal and stored in a table. Thereafter, the features of the table are selectively combined and transformed into a plurality of code sequences, that is, into one dimensional information for comparison with selected reference characters and designation as an associated character upon identification thereof with a reference character in the dictionary, while being rejected upon nonidentification.
In the process of converting the two dimensional information of a character into one dimensional information in this type of character recognition apparatus, the sequence of the plurality of codes becomes different in dependence on the selection of the start point of the one dimensional information. Therefore, it is very important to determine where the starting point is. Although it seems reasonable to select the left upper terminal point as the starting point, there are many drawbacks when the scanning direction to detect the starting point is limited to a fixed direction.
Especially, in the case of recognizing hand written characters, the starting point is often different according to the personality of the writer, as will be described later. In such a case, the character recognition apparatus must be provided with a memory capable of storing several code trains for each reference character.